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Friday, January 25, 2013

Preparation of 5,5-diphenylhygantion - Synthesis of Dilantin - Lu Le Laboratory

The sodium salt of 5,5-diphenylhygantion, Dilantin, is an anticonvulsant used for the treatment of epilepsy. 

                   Preparation of Benzoin - Synthesis of Dilantin )

The synthesis process of 5,5-diphenylhygantion is as follows:

Reaction equation:



1.      Benzil: 0.60 g

2.      Urea: 0.36 g

3.      Potassium hydroxide solution: ~2mL saturated(~14.8M)

4.      Sulfuric acid: 6M
5.      Ethanol 95%


1.      Add 0.60g benzil and 0.36g urea in to a 50mL round-bottomed flask

2.      Add 6 mL 95% ethanol and 1~2mL KOH solution.

3.      Reflux the mixture with stirring for 2.5 hr.

4.      Cool the reaction mixture and remove the sparingly insoluble solid by gravity filtration.

5.      Cool the filtrate further in an ice-water bath and acidify the filtrate with 6M sulfuric (pH 1.5~3). The white powdered solid is obtained.

6.      Collect the product by filtration, and wash it thoroughly with water to remove the inorganic salt.

7.      Recrystallize the crude product from 95% ethanol.

8.      The white needle-shape crystal is obtained.


Experimental Record

Weight of benzil
0.60 g
Weight of final product (Dilantin)
0.36 g
Theoretical Weight of Dilantin
0.72 g
50.0 %


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  3. what is the name of this rearrangement ?

    1. It's a Benzilic Acid Rearrangement.

  4. thank you very much for your help :)

  5. Thanks man, this helped me a lot now!
    And nice job, just keep doing stuff like this!
    Best regards, Marton

  6. thank you so much, this really helps me alot!
    by the way,, could you tell me how you contolled the temperature during refluxing? we did this experiment once, but we failed to synthesize the
    product.. i guess refluxing process caused this..i mean.. did you keep temperature still for 2.5hours or change the temperature from the time it boiled..? it's been long that this content were made,,so it would be hard to answer,.i'm so sorry,, but could you give me some advices if you dont mind..?

  7. good job..procedure with step by step images.